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[acfa-ir 112] Minutes of 70th FFIR/BDSIM meeting on 3/17/2004 and next in 4/8, 13:30

Subject:   [acfa-ir 112] Minutes of 70th FFIR/BDSIM meeting on 3/17/2004 and next in 4/8, 13:30
From:   田内 利明 <toshiaki.tauchi@xxxxxx>
Date:   Mon, 05 Apr 2004 17:25:56 +0900

Dear Colleagues,

We will have a next meeting at 13:30- on 8 (Thu) April, 2004.  The place is
room#325 at the 3rd floor of 3-gokan.  It will be TV(ch#31110) conference.

NOTE!  The date and time are different from usual ones.

Can you also find an appended minutes of 70th FFIR meeting?
Please also see a web site of http://acfahep.kek.jp/subg/ir/minutes.html .
It may take some time to update the web site. So if you do not see the
minute, please wait for about 30 min. .

Comments and questions are welcome.

Best regards,
T.Tauchi  (KEK)

**************************************************************Minutes of
70th FFIR/BDSIM meeting on 3/17/2004

 The meeting was held in a room of 425 at KEK, 10:00-12:00, 3/17/2004. We
discussed on final focus system, FEATHER and dark current at the LINAC.

 (1) Final focus system (S. Kuroda)
 (transparencies, 1 pages, pdf, 55KB)

 Kuroda showed three figures of chromaticity as a function of magnets for
cases of "ATF-FF original", "(a) ξy correction" and "(b) ξx", which have
been discussed at previous meetings. The three cases have the same optical
configuration, while dispersion functions near the IP can be varied by
adjusting a matching section in the upstream. As mentioned in the previous
meeting, the (a) and (b) clearly show local chromaticity corrections. One of
distinct features is a pair of final doublet system with the same optics in
them for geometric aberration corrections. Therefore, the local corrections
can be seen at the two final doublet systems, i.e. SF1F~QB1F and SF2F~QC3F,
where beta functions become large. Next, vibrational tolerances of
quadrupole magnets and tolerances of their strength will be investigated.

 (2) Dark current in LINAC (T.Yamamura)
 (transparencies, 6 pages, pdf, 1.8MB)

 Yamamura has investigated initial conditions of electrons at the cell
surface which can go through the structure (100 cells). There are two major
parameters for the generation of electrons, which are initial position (zi
along a longitudinal axis of the structure) and initial timing (relative
phases to RF pulse; φr,i and φz,i). The electrons were tracked by using
Runge-Kutta method with a time bin of 1psec. The survived electrons were
concentrated in a very small region of |zi|<1.5mm and 5.6< φr < 6.2 radian,
where the initial position is zi=0 at the upstream edge of first cell. There
is a "linear" correlation in them. He also plotted relative phases (φr and
φz) as a function of z for a short lived electron with 
φr,i=φz,i=2.95.
The two phases walk away from each other and quickly get in out of phase (-
π difference). For further investigation, positron cases may be interested.

 (3) FEATHER (N.Delerue)
 (transparencies, FEATHER, 7 pages, pdf, 347KB)

 Nicolas briefly reported recent beam test on the BPM with movable
electrodes. To be able to calibrate the BPM, we need to know the BPM as a
function of the beam position measured by other BPMs. Four informations were
extracted from the BPM signals; each electrode signal, sum and difference of
the electrodes' signals. To ensure synchronization, a first ATF_CONTROL was
issued, the the digital oscilloscope was set into single Acquisition mode,
then a second ATF_CONTROL command was issued for the second data taking. He
showed measurements of the BPM signals with wide, 1mm, 2mm and 4mm gaps as a
function of beam vertical position at the BPM. Signals of each electrodes
varied as the beam position, while the differences distributed rather
widely. For cases of the 2mm and 4mm gaps, correlation plots of sum-signal
and beam intensity were made. No sharp correlation was seen. There may be
wrong synchronization. Since these measurements were the first, he has
mostly concentrated on the data acquisition. He will continue the BPM
calibration. Also, he will try to fully simulate signals in the feedback
system.

 The next meeting will be on 8 April, 2004,13:30 - at 3 gokan, 325 .